there is a settings file created in the web assist/email folder for each instance of the UE behavior.
if you look in the UE code block there will be a require line to attach that settings file similar to:
look for that line to determine the settings file, and look in the settings file for the CC and BCC addresses.
Where the email is sending sometimes, that would mean that either the email is being trapped as spam or the host is not relaying it to the CC address sometimes. you will need to contact the host to determine why it is not being relayed sometimes but works other times.